1. Field of the Invention
The present invention relates to a sealing device concerning a sealing technique. The sealing device in accordance with the present invention is used in a field of a motor vehicle, a construction machine, a farm machine, other general industrial machineries or the like. For example, in the motor vehicle relevant field, the sealing device is used for sealing between a cylinder head cover and a plug tube or between the cylinder head cover and an injection pipe in an internal combustion engine.
2. Description of the Conventional Art
In conventional, as shown in FIG. 12, there has been known a sealing device 53 attached in an opening portion 51a of a housing (a cylinder head cover in the drawing) 51 for sealing between the housing 51 and a tubular member (a fuel injection nozzle in the drawing) 52 inserted to the opening portion 51a of the housing 51, and the sealing device 53 integrally has a mounting portion 54 fixed to the housing 51, and a seal lip 55 brought into close contact with an outer peripheral surface of the tubular member 52 (refer to Japanese Unexamined Patent Publication No. 11-173423, patent document 1).
Since the sealing device 53 having the structure mentioned above is structured such that the mounting portion 54 constituted by a rubber-like elastic body is brought into close contact with an inner peripheral surface of the housing opening portion 51a at an outer peripheral bead 54a thereof, and the seal lip 55 is brought into close contact with an outer peripheral surface of the tubular member 52 at a lip end 55a thereof, the sealing device 53 can sufficiently seal between the housing 51 and the tubular member 52.
In recent years, in a gasoline engine among the internal combustion engine, there has been developed a multi simultaneous ignition system called as a twin plug, and there has been explained that the twin plug has the following advantages.
When igniting gasoline so as to explode, it is possible to more completely burn an air-fuel mixture within a combustion chamber by simultaneously igniting the gasoline at two positions rather than one position. At the same time, since a flame propagation is executed at two positions, a great explosion is instantaneously generated, a torque is increased, a startability of the engine is improved, and it is possible to obtain a sharp accelerating performance. If the accelerating performance is improved, it is possible to reduce a time required for making the engine in a high speed operation, whereby it is possible to improve a specific fuel consumption.
In the twin plug mentioned above, since two ignition plugs are used side by side, two guide tubes guiding the ignition plugs are provide side by side. However, the sealing device 51 in FIG. 12 mentioned above is not structured such that two plug tubes are inserted together therein so as to be sealed.